Amazon Cacao (Theobroma cacao L.) Shade and Manurial Experiment (K2-01) at the Cocoa Research Institute of Ghana. I. First Five Years1

Yaw Ahenkorah and

G. S. Akrofi2

Abstract

Abstract

The experimental layout, initial crop husbandry, preliminary girth measurements and yield results before and after the imposition of 2 years' shade and fertilizer treatments on the Amazon cacao Shade and Manurial Experiment (K2-01) at Tafo are reported.

In assessing the uniformity of the 4-year-old cacao stand analyses of data on girth measurements gave C.V. of 10.26% and 12.86% for subplot and main plots, respectively. These are remarkably lower and highly satisfactory compared with the C.V. of 57.75% for the corresponding yield.

Statistical evaluation of variations between NPK fertilizer, block, cropping seasons, and shade effect is reported. The significant slope effect during the minor crop season was interpreted to be only a seasonal reflection of the probable variation in the available soil moisture. The shade effect of this experiment is compared with a similar and older experiment (Kl) at Tafo. The significant shade effect during the 1964/65 season in both cases varies with time of the year irrespective of the different shade trees.

Shade, K, and PK fertilizer effects are highly significant with the dt shaded cacao yielding almost twice as the plots under heavy shade whilst the fertilizer is about 10% greater. “No shade” with PK treatment has the uniformly highest yield followed by the “medium shade” with PK and the least being “heavy shade” with PK fertilizer. Shade effect is well marked during the main cropping season while that of K is pronounced without overhead shade.

There is a suggestion of rapid depletion of exchangeable K after 7 years of continuous cropping. The Amazon cacao on the WACRI series does not respond to the NPK fertilizer until it is over 5 years old.

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